POS0502 ULTRASOUND THRESHOLDS FOR INFLAMMATORY AND STRUCTURAL LESIONS TODISTINGUISH OSTEOARTHRITIC FROM RHEUMATOID ARTHRITIS PATIENTS
Authors: S. Honstettre, G. Julien, E. Allado, I. Chary Valckenaere, D. Loeuille
Journal: Annals of the Rheumatic Diseases (2022)

Background Rheumatoid arthritis (RA) is the most common chronic inflammatory rheumatic disease affecting small and medium-sized joints symmetrically, leading to poor functional outcomes and structural damages with time. The RA elementary inflammatory lesions, synovitis and tenosynovitis, have been associated with the development and worsening of bone erosions leading to loss of joint function and pain. The median age at diagnosis of RA patients, ranged between 50-60 years old, age at which degenerative and inflammation lesions relative to osteoarthritis (OA) damages may be present and interfere to establish a diagnosis of inflamed and/or structural RA disease. Objectives To assess prevalence, topography and severity of inflammation and erosion on ultrasound (US) in RA and OA patients and to propose US thresholds to classify RA patients. Methods Patients fulfilling ACR 1987 and/or ACR/EULAR 2010 criteria for RA or ACR criteria for hand OA were reprospectively included. Synovitis and tenosynovitis (TS) in B and Power Doppler (PD) modes on seven bilateral joints (carpus, MCP2, 3, 5, MTP2, 3, 5) were scored according to a four-grade scale of severity. Erosive disease was defined by the presence of at least one erosion &gt;2 mm confirmed in 2 perpendicular plans on 30 targeted facet joints. Sensitivity, specificity and OR for the diagnosis of RA were calculated for each elementary (inflammatory and erosive) US lesion. Results 153 patients were included: 107 (31 early &lt;2 years) RA and 46 OA patients. Synovitis (B and PD modes) was observed in 92 (85.9%) RA and 12 (26%) OA patients, respectively (p &lt;0.0001). TS (B and PD modes) was depicted in 61(57%) RA and 4 (8.7%) OA patients, respectively (p &lt;0.0001). 71 (66%) RA and 5 (11%) OA patients responded to the definition of erosive disease (p&lt;0.001). The combination of US erosion and PD+ synovitis provided the best compromise to classify RA patients: sensitivity 49.1% (39.7-58.4)), specificity 97.8% (87.4-99.5) and OR= 43.8 (CI95: 8.2-230.2). For early RA, PD+ TS provided the best compromise: sensitivity 54.8% (37.8-58.4), specificity 97.8% (87.4 -100) and OR= 54.6 (CI95: 9.3- 320.5). Conclusion The combination of PD+ synovitis and erosion in RA and PD+ tenosynovitis alone in early RA offered the best compromise to classify RA versus OA patients. References [1] Scott DL et al. Rheumatoid arthritis. The Lancet. [2] Funck-Brentano et al . Prediction of Radiographic Damage in Early Arthritis by Sonographic Erosions and Power Doppler Signal: A Longitudinal Observational Study. Arthritis Care &amp; Research. [3] Vlychou et al. Ultrasonographic evidence of inflammation is frequent in hands of patients with erosive osteoarthritis. Osteoarthritis and Cartilage. [4] Roux et al. Ultrasonographic criteria for the diagnosis of erosive rheumatoid arthritis using osteoarthritic patients as controls compared to validated radiographic criteria. Joint Bone Spine. [5] Sahbudin et al. The role of ultrasound-defined tenosynovitis and synovitis in the prediction of rheumatoid arthritis development. Disclosure of Interests None declared.